How to solve the bad extrusion of PVC cable material?

2021-12-31   Pageview:551

PVC cable material is a particle prepared by extruding PVC as the base resin, adding stabilizers, lubricants and inorganic fillers, etc., through mixing and kneading. Although it has general performance and is not environmentally friendly, the price is low and the process is simple; PVC cable material is still one of the most used cable materials.

Lubricant is an essential additive in PVC processing. Adding the right amount of lubricant to PVC can reduce the mutual friction between the particles before PVC melting and between the macromolecules in the PVC melt; reduce the mutual friction between the PVC melt and the plastic mechanical contact surface. The right amount of lubricant can improve the fluidity of PVC melt, increase the production efficiency, and prevent the degradation of PVC caused by frictional heat, and improve the appearance quality of products.

According to the function, it can be divided into external lubricant and internal lubricant.

External lubricant is less compatible with PVC, and it is easy to migrate from the inside of resin melt to the surface to form lubricant interface layer, thus reducing the mutual friction between the particles before PVC melt and between PVC melt and plastic mechanical contact surface.

The internal lubricant contains polar groups and has better compatibility with PVC, which can reduce the intermolecular force of PVC, reduce the melt viscosity and improve the melt fluidity.

Polymer paraffin wax etc. is less compatible with polar resin, such as in polar PVC as external lubricant, while in PE, PP and other non-polar resins as internal lubricant. At different processing temperatures, the role of internal and external lubricants will change, such as stearic acid and stearyl alcohol used in the early stage of PVC calendering, due to the low processing temperature, poor compatibility with PVC, mainly play the role of external lubrication, when the temperature increases, the compatibility with PVC increases, it is changed to the role of internal lubricant.

Saturated hydrocarbons can be divided into non-polar hydrocarbons (such as polyethylene wax and polypropylene wax) and polar hydrocarbons (such as chlorinated paraffin, oxidized polyethylene, etc.) according to their polarity.

According to the size of molecular weight, they can be divided into: liquid paraffin wax (C16~C21), solid paraffin wax (C26~C32), microcrystalline paraffin wax (C32~C70) and low molecular weight polyethylene (molecular weight 1000~10000), etc. They are mainly used as non-toxic external lubricants for PVC.


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